Ejection Charge As Second Stage Thrust???

Title pretty much sums it up. Anyone ever tried it?
A tube up through the sustainer to use the force of the boosters ejection charge as its primary thrust.
Kinda like those Drones they use for anti aircraft gunnery training that fire off of a tube of compressed air.
Since you can only fly so high before you are "level one", would say a 2xG80 cluster be able to fire an ejection charge powerfully enough to fire a sustainer off of a spigot tube?
Recovery deployment could of course be triggered via altimeter for both parts if need be.
Just a thought.

Level 1 is not about how high. It's the use of an "H" or higher motor, or a "less than H" motor that is classed as HPR (such as having more than 62.5 grams of propellant in that motor), or a rocket that has more than 113 grams total propellant mass (I have done some clustered or staged rockets that were HPR simply due to the propellant mass of the various model rocket engines).

Anyway...... an ejection charge is very inefficient for thrust itself. The charge has to be confined a bit in some way.... but not confined too much or it'll make something blow apart. If I had a really good reason to try to squeeze extra rocket performance out of using an ejection charge, I might try something where the rocket had a piston inside, and a very short time delay, so that the ejection could kick a "dart" style unpowered upper "stage" (which would be very skinny, low drag, and an onboard system to deploy a recovery device).

Sort of like the Loki-Dart sounding rocket. But I don't think that it is very worthwhile to try to extract extra altitude out of the ejection charge itself.

BTW - if a person wanted to get a lot of altitude out of two G's, clustering would be a poor way to go. Better would be to stage, and not use G80's because of the extreme drag at high velocity as well as extreme stress. I think a good approach would be a PML G40W to a G25. I would suggest the G12 as an upper due to the low thrust and long burn, but it is a bit low on N-sec, is a bit larger in diameter, and has no ejection so the upper stage would require electronic ejection of some type.

If the challenge was say a maximum of 320 N-sec, I might try something like G40W to F10 to F10, with an onboard tracker (would be under 270 N-sec, so maybe some side pod engines added to the first stage, if I wanted to risk a cluster like that. Also in theory, a 4th stage with an E6, but I think it would already be close to having weathercocking issue with 3 stages).

Thanks for dodging the question.

No reason you couldn't use the Boosters Ejection charge to propel the "dart" to additional altitude. How much additional you would gain would be question able, the other trick is getting a rocket light enough that the delay would be short enough to eject the dart straight up (or withing 10 degrees of vertical), of course altimeters would be required and ejection charges for ejection in both stages. It would be easier just to "airstart" the booster charge for the dart.

Some minor corrections. L1 motors are H and I impulse motors only. To certify for L1 in NAR your rocket must be launched on an H or I impulse motor.

Rocket motors with an average thrust greater than 80 N but with a total impulse not exceeding 160 Ns are classified as high power motors by thrust, but you may not use them to certify on a certification flight but you have to be high power certified to use them. Any rocket with more than 125 grams of propellant in all motor is also classified as a high power rocket regardless of the impulse class rating.

4 Estes E9 motors have 143.2 grams of propellant so a rocket containing 4 E9 motors is a high power rocket by propellant mass requiring certification even though the total impulse is only 114 Ns or a 42%G ...

References NFPA 1122, 1125 and 1127.

Bob

I say you should try it with an altimeter in both pieces for comparison.

georgegassaway said:

Anyway...... an ejection charge is very inefficient for thrust itself.

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TopRamen said:

Thanks for dodging the question.

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Thanks for the snide reply? :confused2:

You wrapped the basic question inside of a convoluted scenario including clustered G80's. But the one sentence I said about how an ejection is very inefficient for thrust was all I thought was needed. I gave an example of how to maximize it by using a piston, and a dart.

In replying, you could have said that the answer didn't cover what you were looking for, and you could have clarified the question without the extraneous stuff like clustered G80's.

Instead you used a tone like I was trying to intentionally "dodge" giving you an answer.

OK, I'm done with trying to help. Good luck.

- George Gassaway

Sorry. I was being snide. I apologize.

Wouldn't the component holding the ejecting motor (the booster) have to have a greater mass than the sustainer for this to be effective? Otherwise the ejection would just propel the booster backwards with little of the force being applied to propelling the sustainer forward.

455 Buick said:

Wouldn't the component holding the ejecting motor (the booster) have to have a greater mass than the sustainer for this to be effective?

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I don't think it makes any difference. Newton's laws apply here, so the same force is being applied to the booster as to the sustainer (3rd law). The acceleration then depends on the mass of the sustainer itself (2nd law = F=ma --> a=F/m).

455 Buick said:

Wouldn't the component holding the ejecting motor (the booster) have to have a greater mass than the sustainer for this to be effective? Otherwise the ejection would just propel the booster backwards with little of the force being applied to propelling the sustainer forward.

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If I'm recalling my Newtonian physics properly, both Newton's second and third laws of motion would apply here. Newton's second law states that Force = Mass * Acceleration, which can be rearranged as Acceleration = Force (ejection charge) / Mass. Therefore having a lower mass would result in a greater acceleration.

Newton's third law states that "for every action there is an equal and opposite reaction". So the ejection charge would push "up" on the sustainer with the same force that it would push "down" on the booster. I think this is what 455 Buick has in mind. If my understanding is correct though, the forces acting on each piece of the system are discrete and therefore the ratio of their masses would be irrelevant to their accelerations.

Making the sustainer as light as possible would maximize the effect of the force of the ejection charge, giving it the greatest acceleration, though the mass of the booster would have no bearing on this.

BTW, the spell check doesn't recognize the word "sustainer"?